Chef is at the top of a flight of nn stairs. Chef is initially at level nn and wants to reach to level 0.
In one move Chef can jump move at most 3 levels either up or down. (Note that Chef can choose to remain in the same position if he desires).
Chef cannot move below level 0 or move above level n.
Print the number of ways Chef can reach level 0 using after xx moves.
Note: If it is not possible to reach level 00, you should print 00, since there are no ways Chef can reach level 0.